Question

I have a static array:

myArray: array [0..15] of byte;

I wish to pass this array (not a copy of the array) into a function. Inside the function, I will manipulate the data in array.

Different lengths of STATIC byte array may be passed in to Init at different times. Therefore, I do not wish to declare Init to be able to receive only a certain length of byte array. (e.g. in this case it is a 16 bytes. At other times it may be 65000 bytes)

This is the way I used the function:

Init(@myArray[0]); //passing in pointer to static array

I tried to declare Init like this:

procedure Init(x: array of byte);
begin
//Do some stuff with x, for e.g.
Length(x);  //I do not intend to pass in the length as a parameter, 
            //but determine it in this function itself.  


end;

Is this also a correct way of declaring the Init function parameter?

Answer 1

1. Instead of Init(@myArray[0]) use Init(myArray). Delphi will transfer the myArray by reference
2. You declared x as open array of bytes. The open array parameters are type compatible with the array variables with the same element type. Delphi will transfer fixed array length as a hidden parameters. You can access it with Length(x) and e.g. for i := Low(x) to High(x) do.
3. Open array parameters cannot be set to nil. If you need to set x to nil, then you have to declare x as pointer to Byte or pointer to array[..] of Byte.